Pyrifluquinazon modifies insect behavior by rapidly stopping feeding so that insects starve to death. In the present study, the effects of two nano types of pyrifluquinazon and a non-nano type of pyrifluquinazon on mortality of the green peach aphid, Myzus persicae, were investigated using three different concentrations (25, 50, and 100 ppm). The nano types of pyrifluquinazon were formulated with a different molecular weight and density than that of chitosan (CS 30,000, 0.1% and CS 3000, 0.3%) for stability of unsteady core materials. According to the bioassay and the increased rate of aphids, both types of pyrifluquinazon at all concentrations were effective for controlling M. persicae. The CS 3000 0.3% nano type pyrifluquinazon exhibited a more effective controlled-release feature than that of the other type. The two nano types and the non-nano type pyrifluquinazon were bioassayed against M. persicae, and feeding behaviors were compared using the electrical penetration graph technique. The non-nano type appeared to have the best lethal efficiency at 2 days after treatment at 50 and 25 ppm according to the non-penetration time; however, both CS 30,000 0.1% and CS 3000 0.3% were effective at 14 days after treatment. Furthermore, reaction time slowed from 14 to 30 days after treatment in the CS 3000 0.3% treated aphids. As a result, CS 3000 0.3% had more effective controlled release at both concentrations.